Method and apparatus for producing deformed steel bars



June 1966 YOSHIO TAKAISHI 3,256,727

METHOD AND APPARATUS FOR PRODUCING DEFORMED STEEL BARS Filed July 21, 1965 2 Sheets-Sheet 1 F IO. 1. FIG. 2.

INVENTO YOS HIO TAKA AT TVS.

June 1966 YOSHlO TAKAISHI 3,256,727

METHOD AND APPARATUS FOR PRODUCING DEFORMED STEEL BARS Filed July 21, 1965 2 Sheets-Sheet 2 FIG. IO.

l INVENTOR: F'IGIG. v FIG.I5. w BY YOSH o TAKAISHI United States Patent '0 3,256,727 METHOD AND APPARATUS FOR PRUDUCING DEFORMED STEEL BARS Yoshio Takaishi, 50-149 Kitashirakawa, Ogura-machi,

. Sakyo-lru, Kyoto-shi, Japan Filed July 21, 1965, Bar. No. 473,794

8 Claims. (Cl. 72-234) This application is a continuation-in-part of my prior US. application Serial No. 384,095, entitled Process for Producing Deformed Steel Bars, filed July 21, 1964, now abandoned.

This invention relates to an improved method and apparatus for producing a reinforcing or similar deformed steel bar for use as reinforcing members in concrete structures. The method and apparatus of the present invention forms a steel bar in its natural state (natural temperature) having an elongated body portion of sub stantially circular cross section with a plurality of axially spaced, radially projecting arcuate ribs.

A-primary object of the present invention is to provide apparatus and process for making a cold rolled steel bar of substantially circular cross section with a plurality of transversely arcuated ribs so that the cold deformed bar can be easily bent in every direction at the circular portions thereof.

Another object of the present invention is to provide an improved apparatus and method wherein the original steel bars of circular cross section are first formed, for example, by rolling in their natural state (natural temperature) between cooperating pass grooves of a pair of rolls or passing the bar through dies to form the steel bars to a cross section in the nature of a cocoon shape and thereafter rolling the cocoon-shaped steel bars in their natural state between cooperating pass grooves of a pair of rolls for producing the rolled bar having a body portion of substantially circular cross section and a plurality of axially spaced radially projecting arcuate ribs.

Other objects of the present invention and the various features and details of the method and apparatus of the present invention are hereinafter more fully described with reference to the accompanying drawings in which:

FIG. 1 is a cross sectional view of one form of prior art reinforcing bar taken along line 1-.1 of FIG. 2;

FIG. 2 is a side view of the cold rolled bar in FIG. 1; FIG. 3 is a sectional view of another form of prior art reinforcing bar taken on line 3-3 of FIG. 4;

FIG. 4 is a side view of the reinforcing bar in FIG. 3; I FIG. 5 is a sectional view of an original round steel bar to be deformed in accordance with the present invention;

FIG. 6 is a cross sectional view of the cocoon-shaped bar after the first step of the deforming process;

FIG. 7 is a cross sectional view of the finished reinforcing bar made in accordance with the present invention;

FIG. 8 is a side-elevational view of the reinforcing bar shown in FIG. 7;

FIG. 9 is a side elevational view partly in section of a portion of apparatus of the present invention which forms the deformed bar from the cocoon-shaped steel bar to the finished bar shown in FIGS. 7 and 8;

FIG. 10 shows apparatus in accordance with the present invention for making reinforcing bars; I

FIG. 11 is a fragmentary view taken on lines 11-11 showing the first set of forming rolls for forming an elongated member to a bar of circular cross section;

FIG. 12 is a view taken on line 1212 of FIG. 10 of the second set of forming rolls for forming the bar 'of circular cross section to a cocoon-shaped cross sectron;

FIG. 13 is a fragmentary sectional view taken on lines 1313 of FIG. 9 through the nip of the third set of forming rolls for forming the cocoon-shaped bar into the finished reinforcing bar;

FIG. 14 shows another embodiment of apparatus in accordance with the present invention;

FIG. 15 is a view taken on lines 15-15 of FIG. 14; and

FIG. 16 is a view taken on lines ll616 showing the shape of the die member for forming the bar to a coco0n-shaped cross section.

One of the problems in the prior art type of deformed steel bar shown in FIGS. 1-4 inclusive is that they cannot be bent easily along their longitudinal axis in all direction. It has been found that the rolling process for the bar shown in FIG. 1 which is oval shape in cross section is not economical. When it was attempted to produce the cold deformed bar from the oval-shaped bar through rolls having both a larger diameter and higher revolution, there was such a defect as the bar was pressed transversely into the clearance of the pair of rolls, and it was not possible to obtain the deformed bar without the'lon-gitudinal ribs.

In accordance with the present invention, a method and apparatus is provided for making a reinforcing bar of circular cross section having a plurality of longitudinally spaced, arcuate ribs which may be bent in all directions with the same bending force. To this end, in accordance with the present invention, an elongated workpiece is first formed to provide a bar 1 of circular cross section of the type shown in FIG. 5. The circular bar is then formed into a cocoon-shaped bar 2 with a longitudinal depression 3 on opposite sides as shown in FIG. 6. Thereafter, the bar of cocoon-shaped cross section is passed from the inlet guide 10 through the grooves of rolls 7, 7' to press the bar along the longitudinal axis into round sections to the outlet guide 11 of the deforming rolls 7, 7 as shown in FIG. 9. The rolls are provided with the substantially semi-circular cross sectional cooperating pass groove 9 having a plurality of small transversal grooves 8, so that the rolled bar 6 has been deformed to substantially circular cross section 5 with a plurality of transversely arcuated ribs 4 of small longitudinal thickness and without opposite longitudinal ribs as shown in FIG. 8. The resulted deformed bar can then be bent in every direction in the circular body portion thereof.

In accordance with the present invention, there is provided apparatus for making reinforcing bars of the type described above which is of comparatively simplified construction and wherein the reinforcing bars may be made in a highly economical and precisely controlled manner. To this end, in accordance with the'embodiment of the invention illustrated in FIG. 10, the apparatus includes a first forming means in the form of a pair of forming rolls 2t), 20 which, as illustrated in FIG. 11, have semicircular, circumferentially extending working faces 22 which cooperate to form an elongated workpiece from a given cross section to a circular bar of predetermined cross section and the desired diameter. The apparatus further includes second forming means to form the circular bar to one of cocoon-shaped cross section. The second forming means comprises, in the present instance, a pair of cooperating rolls 24, 24 mounted for rotation about an axis transverse to the rotational axis of the first forming rolls, each roll 24 having a work face 26 of semi-cocoon-shaped cross section to form the circular bar into the cocoon-shaped cross section shown in FIG. 6 of the drawing. The cocoon-shaped bar then passes through the guide member 10 and is fed into the nip of the forming rolls 7, 7' with the largest dimension L of the cocoonshaped bar being transverse to the direction of rotation of the rolls 7, 7' thereby to form the finished elongated bar having a body portion of circular cross section and the transversely arcuate ribs 4.

Another embodiment of apparatus in accordance with the present invention for forming the elongated bars shown and described above is illustrated in FIGS. 14- 16 inclusive. Inaccordance with this embodiment of the invention, the elongated workpiece is first formed to a circular cross section of a predetermined diameter. In the present instance, this is accomplished by drawing the workpiece through a die 30 having a die opening 32 of circular cross section. The bar is drawn through the die 30 by means of a cooperating pair of rolls 34, 34. After the workpiece is formed to a circular configuration, the bar is then passed through a die 36 having a cocoonshaped opening as at 38. The cocoon-shaped bar is then passed through the rolls 7, 7 to form the finished bar having the circular body portion 5. and longitudinally spaced ribs 4.

In the experiments of increasing the speed of cold rolling, I found that the larger the diameter of cold deforming rolls, or the greater the hardness of the bar to be rolled, the more the tendency of the bar to be extended transversely between a pair of rolls during the cold rolling process. The faster the revolution speed of said rolls, the lesser the tendency of the bar to be extended traversely. However, when increasing the deforming speed of the steel bar in cold state, I had to increase" both the diameter and the revolution speed of the cold deforming rolls. As a result, I found that the most important matter is such that the cocoon-shaped cross section of the bar in its natural state (natural temperature) is suitable to high speed deforming rolls.

The special characteristics of the process of the invention are illustrated by a series of examples.

When the cocoon-shaped cold rolled bar of preferred sectional dimension as shown in FIG. 6 is applied to a pair of deforming rolls of 17 cm. diameter, at a speed of 150 rpm, the end product is shown in FIG. 7. The experimental data of the longitudinal height L, and the shortest Width it between the depressions and the largest width m of said cocoon-shaped bars, and also the diameter d of the circular section of the body portion and the maximum height 1 of the ribs on the deformed bars of the invention as shown in the following table.

When I increase only the rotating speed of said rolls, the difference between the width of m and n is reduced. At this time the opposite depressions may be almost diminished.

With regard to theactual rolling process, some difiiculties are frequently encountered to form the deformed bar with the normal circular cross section. However, through precision regulation of the clearance between a pair of rolls, the longitudinal ribs or grooves will not appear on the circular surface of the deformed bar. When the deformed bars of the invention having a diameter from 5.00 mm. to 1.00 mm. are to be applied to concrete reinforcing steel bars, they can be bent in every direction.

While particular embodiments of the present invention have been illustrated and described herein, it is not intended to limit the invention and changes and modifications may be made therein within the scope of the following claims.

I claim:

1. A method of making an elongated reinforcing bar consisting of the steps of working an elongated member of predetermined cross section in a manner so that it is cocoon shaped in cross section and thereafter deforming the cocoon-shaped bar in a manner to form the reinforcing bar having a body portion of circular cross section and a plurality of longitudinally spaced arcuate ribs projecting outwardly from the body portion and extending circumferentially of the body portion for less than the entire circumference thereof.

2. A method of making an elongated reinforcing bar consisting of the steps of working an elongated member of predetermined cross section in a manner so that it is cocoon shaped in cross section, and thereafter passing the cocoon-shaped bar through a pair of cooperating rolls to form a reinforcing bar having a body portion of circular cross section and a plurality of longitudinally spaced arcuate ribs projecting radially outwardly from the body portion and extending circumferentially of the body portion for less than the entire circumference thereof.

3. A method of making an elongated reinforcing bar consisting of the steps of passing an elongated member of circular cross section through a die to form. a cocoonshaped bar and thereafter passing the cocoon-shaped bar through a pair of cooperating rolls to form a reinforcing bar having a body portion of circular cross section and a plurality of longitudinally spaced arcuate ribs projecting radially outwardly from the body portion and extending circumferentially of the body portion for approximately one-half the circumference thereof.

4. Apparatus for making an elongated reinforcing bar comprising a body portion of circular cross section and a plurality of longitudinally spaced arcuate ribs projecting radially outwardly from the body portion and ex tending circumferentially of the body portion for less than the entire circumference thereof comprising first forming means for working an elongated member to a circular cross section, second forming means for working the elongated member of circular cross section in a manner so that it is cocoon shape in cross section and third forming means for deforming the cocoon-shaped elongated member to provide a bar having a body portion of circular shape with a plurality of longitudinally spaced arcuate ribs extending circumferentially of said body portion for less than the entire circumference thereof.

5. Apparatus for making an elongated reinforcing bar consisting of a body portion of circular cross section and a plurality of longitudinally spaced arcuate ribs projecting radially outwardly from the body portion and extending circumferentially of the body portion for less than the entire circumference thereof comprising a first pair of cooperating rolls through which an elongated member is passed to formit into a circular cross section, a second pair of cooperating rolls which forms the circular cross sectional bar to a cocoon-shaped cross section, a third set of cooperating rolls having means whereby the cocoon-shaped bar is formed to provide the body portion of circular cross section and the longitudinally spaced arcuate ribs extending circumferentially of said body portion for less than the entire circumference thereof.

6. Apparatus as claimed in claim 5 including guide means adjacent the third set of rollers for guiding the cocoon-shaped bar to the nip of the third set of rollers.

7. Apparatus as claimed in claim 5 wherein the circumferentially extending working surfaces of the second forming rolls are of semi-cocoon-shaped configuration.

8. Apparatus for making an elongated reinforcing bar comprising a body portion of circular cross section having a plurality of longitudinally spaced arcuate ribs projecting radially outwardly of the body portion comprising a first pair of cooperating rolls having semi-circular circumferentially extending Working surfaces to form an elongated member of circular cross section, a die of cocoon-shaped cross section through which the bar is 6 passed to form it into a cocoon-shaped cross section, and forming means for deforming the cocoon-shaped bar into a shape having the circular body portion and the arcuate ribs.

References Cited by the Examiner FOREIGN PATENTS 213,363 2/1961 Austria.

25,458 1909 Great Britain. 303,187 2/ 1955 Switzerland.

CHARLES W. LANHAM, Primary Examiner.

H. D. HOINKES, Assistant Examiner. 

1. A METHOD OF MAKING AN ELONGATED REINFORCING BAR CONSISTING OF THE STEPS OF WORKING AN ELONGATED MEMBER OF PREDETERMINED CROSS SECTION IN A MANNER SO THAT IT IS COCOON SHAPED IN CROSS SECTION AND THEREAFTER DEFORMING THE COCOON-SHAPED BAR IN A MANNER TO FORM THE REINFORCING BAR HAVING A BODY PORTION OF CIRCULAR CROSS SECTION AND A PLURALITY OF LONGITUDINALLY SPACED ARCUATE RIBS PROJECTING OUTWARDLY FROM THE BODY PORTION AND EXTENDING CIRCUMFERENTIALLY OF THE BODY PORTION FOR LESS THAN THE ENTIRE CIRCUMFERENCE THEREOF. 